There are various electric home appliances that operate on supplied power including refrigerators, washing machines, dishwashers, air conditioners, cooking apparatuses, televisions, vacuum cleaners, electric pads and electric rice cookers.
Such electric home appliances are supplied alternating current power supply from an external power supply when put into operation. A watt-hour meter is installed in every house to measure watts consumed in the house.
Recently, there is a growing interest and demand for power-saving, for example, using power-saving products or using relatively low-priced off-peak electricity.
Some electric home appliances have power or wattage consumption determined during the manufacturing process and noted on the appliance.
However, to measure the power or wattage substantially consumed by a specific home appliance, an auxiliary watt-hour meter (namely, a power meter) is typically connected to the specific home appliance.